ttcn3-bsc-test-sccplite/osmo-bsc.cfg: configure 3 additional TRX instances for BTS2
This should have been done as part of [1] in order to avoid
regressions in ttcn3-bsc-test-sccplite.
Change-Id: I2d0045533814a2bacc384c06287066f2209a5f38
Fixes: [1] Iba4fbd5c9ed59783df4ac64e68b2beef73a812ff
Related: SYS#5460
